Analog Filter

Summary

The most commonly used analog filter design techniques are the Butterworth, Chebyshev I, II, and elliptic ones. The parametric frequencies together with the filter order can be predetermined using ‘buttord ()’, ‘cheb1ord ()’, ‘cheb2ord ()’, and ‘ellipord ()’. The frequency input argument should be given in two‐dimensional vector for designing band‐pass filter or band‐stop filter (BSF). For high‐pass filter/BSF, the string ‘high’ / ‘stop 1 should be given as an optional input argument together with ‘s’ for analog filter design. MATLAB has the built‐in functions ‘butt ()’, ‘cheby1 ()’, ‘cheby2 ()’, and ‘ellip ()’ for designing the different types of analog/digital filter. This chapter introduces some MATLAB functions that can be used to determine the parameters of the circuits so that they can implement a given transfer function. The MATLAB function ‘imp_matcher_L ()’ can be used to find possible L‐type filter for impedance matching between given source/load impedances.